St. Petersburg Adds Minerals to Water Supply
The city's added treatment has cut hard-water complaints by 90 percent after drought raised mineral levels in its drinking water.
Updated on Nov. 14, 2026 in Utilities
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St. Petersburg began adding ortho phosphate and polyphosphate to its drinking water at the Cosme Water Treatment Plant in Odessa about two months ago. Hard-water complaints fell from 30 to three after the treatment began.
Why it matters
The drought reduced surface water, so the city pulled more groundwater containing calcium and magnesium minerals into its drinking water blend. The added treatment addresses staining and spotting while the city's supply returns closer to normal.
Hard-water complaints in St. Petersburg fell from 30 to three, a 90 percent drop, after treatment began. Plant operators test the water every four hours, and the stub does not report whether complaint levels will hold once the blend normalizes.
The players
Tampa Bay Water
Tampa Bay Water is the regional wholesale water utility serving the Tampa Bay area, which supplies desalinated and groundwater sources to member governments.
The details
Polyphosphate binds mineral hardness to reduce staining and spotting, while ortho phosphate places a thin protective layer on the inside of pipes. Tampa Bay Water also pulled more groundwater in the spring and summer, and its reservoir reached a low of 2.1 billion gallons in July before recovering to over 15 billion gallons.
Timeline
Spring and summer 2026: Tampa Bay Water pulled more groundwater due to drought.
July 2026: Tampa Bay Water's reservoir reached a low of 2.1 billion gallons.
About September 2026: The city began adding ortho phosphate and polyphosphate to its water.
October 2026: Water use fell 16 percent compared to one year earlier.
Industry Context
Regional supply conditions moved from Stage III to Stage II in November 2026 under Tampa Bay Water's drought-stage framework, easing the pressure that pushed St. Petersburg toward more groundwater. The city's chemical treatment response reflects how utilities adjust water chemistry when source mixes change.
Residents in St. Petersburg are seeing fewer hard-water spots and stains as the added treatment takes effect. The city plans to keep the treatment in place even as the drinking water blend returns closer to normal.
The takeaway
Utilities can adjust water chemistry to offset mineral changes that come with shifting source mixes during drought. Households in affected areas may notice fewer spots and stains as treated water reaches their taps.
Further reading
For related coverage, see Utilities in our business section.
Source note: This article includes information reported by Spectrum News Bay News 9.
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